I had a local shop build a hemi shortblock for me and I am re-assembling it now,(had to take it apart due to insufficient rod side clearance)they set the piston to wall clearance at 0065 ,at their discretion,I did not have a spec sheet from arias.I called arias today and the guy there said the pistons are 4032 and should be run at 0025.What now?,do I order new pistons,have the skirts coated on these ones or just run it? this is a stock street/restoration engine,4.26 bore 3.75 stroke.......

I was reading on another site they can coat it to +.002 and that would take up .004 but the combustion area above the rings would be loose and that may not be so good.Depending on your budget I think new is best.

I`d be having them make it right then find another machine shop........

Run it

Wont happen,nobody takes responsibility for anything anymore,but I am done with them for sure...

I'd run it. .006-.008 is pretty common on forged pistons. Like was already mentioned, coat it if your really concerned. Good luck

The clearance on the pistons is not the only reason why I`d look elsewhere, it`s the too tight rod clearances also..........they got it all backwards period.............

For sure. As I'm sure you know, tight rod side clearance can lead to a major failure. If your piston to wall is a little loose, it's no worse off than it would have been with some normal wear in a couple years. $1200+/- for a new set of slugs is more than I would spend to solve a minor problem that probably won't be noticeable other than a little noise when its cold. I've assembled engines putting used pistons back in their bores after a straighten up hone that had .010+ clearance with no issue except noise. Not ideal, but not a disaster either.

FOr ours we followed JE instructions and got a 0.005" skirt clearance for our 4" bore JE pistons. So honed to 4.005".

Dosent .0025 sound tight for a forged piston???

My new Diamonds call for .006". My Weisco were run at .007". Line to Line Coatings in Michigan can build them up if needed. Plenty of positive reviews even on high buck race motors.
Doug

I have no personal experience with them, but I have read that 4032 aluminum has more silicone than traditional forged pistons so they expand 15% less. Thus they can be run tighter.

If they should definetly be at .0025 then you could knurl the pistons and then file fit them as I have done that on worn engines before when I used stock bore pistons on cylinders .002 or .003 oversize. Knurling raised the surface and once they are knurled they may not even fit in the cyl as you then file fit them. It actually works very good and is an old trick of years ago. But the knurls hold some oil in them so it keeps some oil on the side of the piston. I ran knurled pistons in a 383 that worked good and did not burn a drop of oil. But be sure as .0065 sounds in the ballpark for a forged piston. I know I run my 440Source pistons at about .006. Ron

Do you know the Compression Distance on the Piston ? or the break point on the skirt ?(pin center DOWN to the tang end)
While 4032 alloys do run tighter than 2618 alloys, I would not really sweat the .0065 Clrc on a long skirt like a stock type piston, which sounds like you have ?
A little high yes, but for stock street type stuff generally speaking, 4032 cam & barrel stuff goes in around .0030" to .0035", with an additional .001" to .003" advised depending on rpm, compression, nitrous or boost(4032 are only good for very light N02 or boost anyways).
They might rattle a bit at .0065", but they'll run fine, 20W-50 maybe to quiet them down ?

Ummmm, YEA. I wouldn't do it.

I put a basterd 360 motor together out of mismatched pistons and block. It has .007 clearance with kb hypers. thats a big no no i guess. just dont tell some circle track guys that, some of them run them way loose. That 360 doesn't make any scary noises at all. Maybe it will someday. Oh well.

Yep! Not gonna be a problem.